The present invention relates to a method of and system for manufacturing powder moldings having a undercut portion, etc.
Conventionally, powder moldings having, for example, a undercut portion, are manufactured as follows: By way of example, a cam sprocket 100, as one of such powder moldings, having a undercut portion 103 between teeth trains 101, 102 as shown in FIGS. 8a and 8b is formed in accordance with a process as shown in FIGS. 8c to 8e.
Specifically, a powder 107 within a die 106 is pressed by upper and lower punches 104, 105 to form a wide sprocket molding 108, which is sintered then machined to cut the undercut portion 103.
However, with such conventional manufacturing method, a machining process of cutting the undercut portion 103 is increased, resulting in a cost up. Therefore, a direct formation of the undercut portion 103 in a powder molding process is requested.
However, if the undercut portion 103 is tried form according to the conventional manufacturing method, a part 110 of the die 106 enters the undercut portion 103 as shown in FIG. 8f, resulting in impossible removal of a finished product 111.
On the other hand, referring to FIGS. 9a and 9b, JP 54-41749 discloses a system having dies 106A, 106B which divide in the transverse direction. However, with this system, teeth 101, 102 of a cam sprocket 100 are caught on the dies 106A, 106B, resulting in impossible removal of the cam sprocket 100.
It is, therefore, an object of the present invention to provide a method of and a system of manufacturing powder moldings having a undercut portion, etc. which enables direct formation of the undercut portion, etc. by powder molding.